cbfstool: remove gcc-specific -Og flag

The new -Og optimization level is only available in gcc version 4.8
or higher. Clang fails on this too as of now (with "invalid integral
value 'g' in '-Og'"). The gain of this does not outweigh this
limitation at all. The flag was added in 0e53931.

Change-Id: I2b2dfc786369653d768f25be94b53329451ae1b4
Signed-off-by: Stefan Tauner <stefan.tauner@gmx.at>
Reviewed-on: http://review.coreboot.org/9999
Tested-by: build bot (Jenkins)
Reviewed-by: Sol Boucher <solb@chromium.org>

util/cbfstool/Makefile

@@ -2,7 +2,7 @@ obj ?= .
 
 HOSTCC ?= $(CC)
 
-CFLAGS += -Og -g3
+CFLAGS += -g3
 CFLAGS += -std=c99 -Werror -Wall -Wextra
 CFLAGS += -Wcast-qual -Wmissing-prototypes -Wredundant-decls -Wshadow
 CFLAGS += -Wstrict-prototypes -Wwrite-strings